Achmatowicz rearrangements

The synthesis of carbacephems 183 and 186 involving C(4)-N(5) bond formation has been described. Carbacephem 183 has been prepared through aza-Achmatowicz rearrangement of 4-(2-furyl) azetidinones (Scheme 32) <1996CC881, 1998SL105>. Azetidinone 175 was obtained by the formal cycloaddition of suitable ketenes with iV-/>-anisyl-2-furylimines. 

The oxidation of furyl-2-carbinols can prodnce 6-hydroxy-2//-pyran-3(6//)-ones (the Achmatowicz rearrangement), which have several synthetic nses, the most important in the heterocyclic context being for the formation therefrom of pyrylinm-3-olate species (11.1.7). The oxidation can be condncted with meto-chloroperbenzoic acid, vanadinm(lll) acetylacetonate with f-butyl peroxide, or with singlet oxygen (18.7). 

Falenczyk C, Polloth B, Hilgers P, KOnig B. Mechanochemically initiated Achmatowicz rearrangement. Synth Commun 2014 45 348-54. 

In the asymmetric total synthesis of (+)-didemniserinoHpid B (14JOC6987), the key Achmatowicz rearrangement/bicycloketaUzation sequence was facilitated by m-CPBA then CSA to give the bicycHc acetal as a single diastereomer. The final product (+)-didemniserinoHpid B was successfully obtained after further manipulations in a total of 19 steps from the starting furan with 0.62% overall yield. 

Zhang et al. reported a synthesis of the minor alkaloid (+)-6-q)i-castano-spermine (655) by a route in which aza-Achmatowicz rearrangement was used to build the six-membered ring (Scheme 91). The optically active... 

Eight Steps in One Process Beyond Achmatowicz Rearrangement... 

Dioxaporphyrin undergoes an Achmatowicz rearrangement on reaction with alumina to give the 3-pyranone dioxacorrole skeleton (Scheme 161) ° ... 

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